Look at Obamacare. Most health policy wonks see it as a pretty tame attempt to fix some issues with insurance and most people support mandatory coverage for preexisiting conditions. But it's been constantly on the defensive as government interference in free markets despite attempts in it to create a more transparent insurance market.
My wealthy suburb of Seattle attempted to block light rail despite desperate need for transit essentially because they basically don't like and don't want public transit. They don't see it as a social good.
People who want drug policy changes have tried to pass every reform you can think of and by and large it hasn't really mattered how minor or radical it is. The rhetoric against reform is the same whether we're talking about recreation marijuana, safe injection sites or decriminalization. There is a segment that believe using anything other than the boot of the law upon offenders is enabling and will degrade society. And there is a segment of society that believe drug abuse isn't a moral flaw but a health concern. Again, that's a belief stemming out of values and nothing else.
To your example, there are many places where public day care would be extremely controversial because people just don't believe in taxes nor the government taking care of kids. They are already often skeptical of public schools. Frankly, the main difference between Colorado in 2012 and 2018 is probably more to do with demographic shifts than how "radial" the policy is.
In a nutshell I'm saying, all of it, everything comes down to these basic beliefs. There can be no conversation about what the government do if one side believes the government should be trusted with nothing. There can be no conversation about what we should do with tax dollars if one side believes there should be no taxes. There can be no conversation about how to reform drug policy if one side only believes in strict punishment.